package com.javaymw.demo.utils;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;

/**
 * 工作日计算工具类<br/>
 * 目前仅支持2017,2018年
 *
 * @author Corvey
 * @Date 2018年11月9日16:53:52
 */
public class WorkdayUtils {

    /** 预设工作日数据的开始年份 */
    private static final int START_YEAR = 2017;

    /** 预设工作日数据的结束年份 */
    private static final int END_YEAR = 2021;

    /** 起始日期处理策略 */
    private static final BoundaryDateHandlingStrategy START_DATE_HANDLING_STRATEGY = date -> {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.HOUR_OF_DAY) < 12; // 如果开始时间在中午12点前，则当天也算作一天，否则不算
    };

    /** 结束日期处理策略 */
    private static final BoundaryDateHandlingStrategy END_DATE_HANDLING_STRATEGY = date -> {
        return true;	// 结束时间无论几点，都算作1天
    };

    /** 工作日map，true为补休，false为放假 */
    private static final Map<Integer, Boolean> WORKDAY_MAP = new HashMap<>();

    private static final SegmentTree SEGMENT_TREE;

    static {
        initWorkday(); // 初始化工作日map

        // 计算从START_YEAR到END_YEAR一共有多少天
        int totalDays = 0;
        for (int year = START_YEAR; year <= END_YEAR; ++year) {
            totalDays += getDaysOfYear(year);
        }
        int[] workdayArray = new int[totalDays];	// 将工作日的数据存入到数组
        Calendar calendar = new GregorianCalendar(START_YEAR, 0, 1);
        for (int i = 0; i < totalDays; ++i) {
            // 将日期转为yyyyMMdd格式的int
            int datestamp = calendar.get(Calendar.YEAR) * 10000 + (calendar.get(Calendar.MONTH) + 1) * 100 + calendar.get(Calendar.DAY_OF_MONTH);
            Boolean isWorkDay = WORKDAY_MAP.get(datestamp);
            if (isWorkDay != null) { // 如果在工作日map里有记录，则按此判断工作日
                workdayArray[i] = isWorkDay ? 1 : 0;
            } else { // 如果在工作日map里没记录，则按是否为周末判断工作日
                int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
                workdayArray[i] = (dayOfWeek != Calendar.SATURDAY && dayOfWeek != Calendar.SUNDAY) ? 1 : 0;
            }
            calendar.add(Calendar.DAY_OF_YEAR, 1);
        }
        SEGMENT_TREE = new SegmentTree(workdayArray);	// 生成线段树
    }

    /**
     * 计算两个日期之间有多少个工作日<br/>
     * @param startDate
     * @param endDate
     * @return
     */
    public static int howManyWorkday(Date startDate, Date endDate) {
        if (startDate.after(endDate)) {
            return howManyWorkday(endDate, startDate);
        }

        Calendar startCalendar = Calendar.getInstance();
        startCalendar.setTime(startDate);
        int startDays = getDaysAfterStartYear(startCalendar) - 1;	// 第一天从0开始

        Calendar endCalendar = Calendar.getInstance();
        endCalendar.setTime(endDate);
        int endDays = getDaysAfterStartYear(endCalendar) - 1;	// 第一天从0开始

        if (startDays == endDays) {	// 如果开始日期和结束日期在同一天的话
            return isWorkDay(startDate) ? 1 : 0;	// 当天为工作日则返回1天，否则0天
        }

        if (!START_DATE_HANDLING_STRATEGY.ifCountAsOneDay(startDate)) { // 根据处理策略，如果开始日期不算一天的话
            ++startDays;	// 起始日期向后移一天
        }

        if (!END_DATE_HANDLING_STRATEGY.ifCountAsOneDay(endDate)) { // 根据处理策略，如果结束日期不算一天的话
            --endDays;	// 结束日期向前移一天
        }
        return SEGMENT_TREE.query(startDays, endDays);
    }

    /**
     * 是否为工作日
     * @param date
     * @return
     */
    public static boolean isWorkDay(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int days = getDaysAfterStartYear(calendar) - 1;
        return SEGMENT_TREE.query(days, days) == 1;
    }

    /**
     * 	计算从开始年份到这个日期有多少天
     * @param calendar
     * @return
     */
    private static int getDaysAfterStartYear(Calendar calendar) {
        int year = calendar.get(Calendar.YEAR);
        if (year < START_YEAR || year > END_YEAR) {
            throw new IllegalArgumentException(String.format("系统目前仅支持计算%d年至%d年之间的工作日，无法计算%d年！", START_YEAR, END_YEAR, year));
        }
        int days = 0;
        for (int i=START_YEAR; i<year; ++i) {
            days += getDaysOfYear(i);
        }
        days += calendar.get(Calendar.DAY_OF_YEAR);
        return days;
    }

    /**
     * 计算该年有几天，闰年返回366，平年返回365
     * @param year
     * @return
     */
    private static int getDaysOfYear(int year) {
        return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0 ? 366 : 365;
    }

    /**
     * 初始化工作日Map<br/>
     * 日期格式必须为yyyyMMdd，true为补休，false为放假，如果本来就是周末的节假日则不需再设置
     */
    private static void initWorkday() {
        // ---------------2017------------------
        WORKDAY_MAP.put(20170102, false);
        WORKDAY_MAP.put(20170122, true);
        WORKDAY_MAP.put(20170127, false);
        WORKDAY_MAP.put(20170130, false);
        WORKDAY_MAP.put(20170131, false);
        WORKDAY_MAP.put(20170201, false);
        WORKDAY_MAP.put(20170202, false);
        WORKDAY_MAP.put(20170204, true);
        WORKDAY_MAP.put(20170401, true);
        WORKDAY_MAP.put(20170403, false);
        WORKDAY_MAP.put(20170404, false);
        WORKDAY_MAP.put(20170501, false);
        WORKDAY_MAP.put(20170527, true);
        WORKDAY_MAP.put(20170529, false);
        WORKDAY_MAP.put(20170530, false);
        WORKDAY_MAP.put(20170930, true);
        WORKDAY_MAP.put(20171002, false);
        // ------------------2018----------------
        WORKDAY_MAP.put(20180101, false);
        WORKDAY_MAP.put(20180211, true);
        WORKDAY_MAP.put(20180215, false);
        WORKDAY_MAP.put(20180216, false);
        WORKDAY_MAP.put(20180219, false);
        WORKDAY_MAP.put(20180220, false);
        WORKDAY_MAP.put(20180221, false);
        WORKDAY_MAP.put(20180224, true);
        WORKDAY_MAP.put(20180405, false);
        WORKDAY_MAP.put(20180406, false);
        WORKDAY_MAP.put(20180408, true);
        WORKDAY_MAP.put(20180428, true);
        WORKDAY_MAP.put(20180430, false);
        WORKDAY_MAP.put(20180501, false);
        WORKDAY_MAP.put(20180618, false);
        WORKDAY_MAP.put(20180924, false);
        WORKDAY_MAP.put(20180929, true);
        WORKDAY_MAP.put(20180930, true);
        WORKDAY_MAP.put(20181001, false);
        WORKDAY_MAP.put(20181002, false);
        WORKDAY_MAP.put(20181003, false);
        WORKDAY_MAP.put(20181004, false);
        WORKDAY_MAP.put(20181005, false);
    }

    /**
     * 边界日期处理策略<br/>
     * 在计算两个日期之间有多少个工作日时，有的特殊需求是如果开始/结束的日期在某个时间之前/后（如中午十二点前），则不把当天算作一天<br/>
     * 因此特将此逻辑分离出来，各自按照不同需求实现该接口即可
     * @author Corvey
     * @Date 2018年11月12日15:38:16
     */
    private interface BoundaryDateHandlingStrategy {
        /** 是否把这个日期算作一天 */
        boolean ifCountAsOneDay(Date date);
    }

    /**
     * zkw线段树
     * @author Corvey
     */
    private static class SegmentTree {

        private int[] data; // 线段树数据
        private int numOfLeaf; // 叶子结点个数

        public SegmentTree(int[] srcData) {
            for (numOfLeaf = 1; numOfLeaf < srcData.length; numOfLeaf <<= 1);
            data = new int[numOfLeaf << 1];
            for (int i = 0; i < srcData.length; ++i) {
                data[i + numOfLeaf] = srcData[i];
            }
            for (int i = numOfLeaf - 1; i > 0; --i) {
                data[i] = data[i << 1] + data[i << 1 | 1];
            }
        }

        /** [left, right]区间求和，left从0开始 */
        public int query(int left, int right) {
            if (left > right) {
                return query(right, left);
            }
            left = left + numOfLeaf - 1;
            right = right + numOfLeaf + 1;
            int sum = 0;
            for (; (left ^ right ^ 1) != 0; left >>= 1, right >>= 1) {
                if ((~left & 1) == 1)	sum += data[left ^ 1];
                if ((right & 1) == 1)	sum += data[right ^ 1];
            }
            return sum;
        }
    }

    public static Date strToDate(String strDate) {
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH");
        ParsePosition pos = new ParsePosition(0);
        Date strtodate = formatter.parse(strDate, pos);
        return strtodate;
    }

    public static void main(String[] args) throws ParseException {
        String start = "2021-11-01 00:00";
        String end = "2021-11-31 23:59";
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        System.out.println(String.format("%s 到 %s, 有%d个工作日！", df.format(strToDate(start)), df.format(strToDate(end)), howManyWorkday(strToDate(start), strToDate(end))));
    }
}
